Like humans, this dinosaur crawled before it walked
像人类一样，恐龙在双足行走前也经历的爬行阶段。
Dinosaurs like the "mouse lizard" are among the few animals that made this particular shift in age-related locomotion, fossils suggest.
化石表明，像“鼠蜥蜴”这样的恐龙是少数种类会随着年龄的增长而从爬行变为直立行走。
BY JASON BITTEL
PUBLISHED MAY 20, 2019
IT’S A SPECIAL moment when a baby learns how to go from crawling on all fours to walking on two legs, especially considering how rare this transition is in the animal kingdom. Only a few other species are thought to make the shift from crawling to upright walking as they age—and they’re all dinosaurs.
当婴儿学会如何从四肢爬行到双腿行走是非常特殊的时刻，尤其是考虑到这种转变在动物界是多么罕见。只有少数其它物种被认为会随着年龄的增长而从爬行变为直立行走，它们都是恐龙。
Now, researchers have added compelling new evidence for one member on that list: a sauropod named Mussaurus patagonicus. (Also see fossil footprints from sauropods that lived in what’s now Scotland.)
现在，研究人员为名单上的一个成员添加了令人信服的新证据：一种叫鼠龙的蜥脚类动物。（在苏格兰也可以看到蜥脚类动物的化石足迹。）
When Mussaurus hatched, it would have been small enough to fit cozily inside a human hand, earning it a genus name that means “mouse lizard.” But after just eight years of gobbling up ferns and other plants, the same creature would have weighed more than a ton.
当鼠龙孵化出来时，它会小到足以舒适地放在人的手上，这就为它赢得了一个“老鼠蜥蜴”的名号。但在吞食蕨类和其他植物仅仅八年之后，同样的生物的重量会超过一吨。
This dramatic explosion in body size and shape brought with it a shift in the way the animal moved, scientists argue in a new study published today in the journal Scientific Reports.
科学家们在今天发表在《Scientific Reports》杂志上的一项新研究中称，这种体型的巨大变化改变了动物的运动方式。
Using a remarkable series of nearly complete fossils that depict three key stages of life, the scientists were able to create interactive 3-D models of the early Jurassic dinosaur and work out where its center of body mass would have been as it aged. Early in life, the animal’s large head and neck would have tilted its body forward onto the support of well-developed forearms. But as its tail grew, the center of gravity would have shifted to the pelvic region, drawing the animal upward into a stance that allowed for walking on two legs.
利用一套几乎完整的可体现生命三个关键阶段的恐龙化石，科学家们能够创造出早期侏罗纪恐龙的交互式三维模型，并找出其身体中心随着年龄增长的位置。在生命的早期，动物的大脑袋和大脖子会把身体重心前倾，这时发育良好的前臂的需要支撑身体。但是随着尾巴的增长，重心会转移到骨盆区域，将动物向上拉成可以用两条腿行走的姿势。
“We don’t know if this pattern applied to all sauropods,” says study leader Alejandro Otero, a paleontologist at the La Plata Museum in Argentina. “But the fact that this [group of animals] shifted their movements in a way so similar to humans is fascinating.”
“我们不知道这种模式是否适用于所有的蜥脚类动物，”研究负责人 Alejandro Otero，阿根廷拉普拉塔博物馆的古生物学家说到。“但这群动物以一种与人类非常相似的方式改变了它们的运动模式，这一事实令人着迷。”
原文链接：https://www.nationalgeographic.com/science/2019/05/mouse-lizard-dinosaur-crawled-then-walked-baby-mussaurus-patagonicus/?cmpid=org=ngp::mc=social::src=twitter::cmp=editorial::add=tw20190520science-uprightwalkingdino::rid=&sf212992552=1
